利用海底地震仪和陆地固定台站记录联合研究2016年6月18日福建漳浦海域M_S3.3级地震震源参数

Joint inversion source parameters of June 18, 2016 M_S 3.3 earthquake in Zhangpu, Fujian Province with OBS and inland stations data

本文利用海底地震仪(OBS)观测到的2016年6月18日漳浦海域M_S 3.3级地震波形,结合陆地固定台网记录,采用NonLinLoc方法对该地震进行了重定位,结果与福建台网定位结果较为一致.采用两种不同方法研究了震源机制解,P波初动极性方法确定了该次地震的共轭断层面解的走向/倾角/滑动角为91/85/-176或0/87/-5,是发生在滨海断裂带附近九龙江断裂沿线上的一个走滑型地震,而陆地台站记录的波形拟合反演结果得到的断层面解为179/79/30和83/61/167.为了评估OBS对震源参数反演的贡献,利用自举法(Bootstraping)评估了单独使用陆地台站记录和联合反演得到的定位和断层面解的方差,结果表明OBS数据的加入明显减小了地震水平位置的方差,而由于该次地震的机制解特性,OBS数据对机制解反演结果的改善程度较为有限.综上,OBS可以有效记录到海域地震信号,并用于地震定位、机制解等研究中,对陆地台网形成了较好的补充.

We relocated the M_S 3.3 earthquake in the Zhangpu area, Fujian on June 18, 2016 with the pickings on Ocean Bottom Seismometers(OBS) and inland stations. The relocated result is consistent with the result of Fujian seismic network center. Two methods are used to study the focal mechanism. Applying P wave first motion method, we obtain the fault plane solution of the earthquake is 91/85/-176. According to the result we conside the earthquake is a strike-slip earthquake that occur nearby the Jiulongjiang fault. At the same time, the fault plane solutions are 179/79/30 and 83/61/167 from the waveform fitting inversion. In order to evaluate the constribution of OBS, we using the Bootstraping method obtain the variance of location and fault plane soulutions from the only land station records and joint inversion. The results show that the addition of OBS data significantly reduces the varinance of seismic level position. However, because of the mechanism characteristics, OBS data is limited to improve the result of facal mechanism. In summary, OBS can effectively record the seismic signals in the sea area, and apply in the earthquake location, mechanism solution and other research. The OBS date can complement the lack of land network data.